Improved chemical deposition and thermal emittance of tin (iv) oxide (SnO2) thin films for photothermal conversion of solar energy and possible applications

Abstract

Thin films of tin (iv) oxide (SnO2) were deposited on six polished sample plates of stainless steel 430 using improved chemical bath deposition (CBD) method at 302 K and pH value of 12.4 for different deposition time of 16 to 36 h at 4 h interval, respectively. Ethylenediamine tetra acetate (EDTA) was used to stabilize the deposition at the required pH value. The thermal emittance values of the polished and coated sample plates were determined before and after the deposition of films, respectively, using thermocouple potentiometer. The average thermal emittance value of the uncoated polished sample plate is 0.15 ± 0.01 while thermal emittance values of the coated sample plates vary from 0.15 to 0.19 ± 0.01. The film thickness of the coated sample plates varies from 33.73 to 77.59 µm. These low thermal emittance values compare well with those obtained for oxidized stainless steel selective surfaces. The coated sample plates with most favorable conditions of thermal emittance 0.17 to 0.18 ± 0.01 and film thickness 45.70 to 69.18 µm could find applications in photothermal conversion of solar energy. The improved chemical bath deposition technique could be employed at different pH values with suitable deposition time to fabricate selective surfaces for use in solar energy applications. Key words: Improved chemical bath deposition (CBD) method, thermal emittance of tin (iv) oxide (SnO2), thin films and possible applications in solar thermal devices.